It’s a great time to be in biotech—new therapeutics are breaking ground faster than we can say “monoclonal antibody” and the technologies behind them are heavy with promise and potential.
Our mission is to keep your industry knowledge up to date and the WEEKLY is here to give you a smart primer on the basics. Below we have outlined several of the therapeutics and innovators making waves in the industry.
GENOME-EDITING: IT’S ALL ABOUT THE BREAK
Genome-editing is the ability to selectively disable or edit the sequence of specific genes. This genome-based therapy is made possible thanks to the cell’s natural ability to repair DNA damage. DNA damage occurs as double-stranded breaks (DSB) because both strands of the double-stranded DNA helix are broken, similar to a two lane bridge that has a section break and fall off after experiencing an earthquake.
There are two types of DNA repair pathways the cell uses to fix DSBs: Non-Homologous End-Joining and Homology Directed Repair.
- Non-Homologous End-Joining (NHEJ) closes the gap between the break by joining the two sections back together—imagine pushing the two sides of the bridge together, without including the section that broke off. An unintended byproduct of NHEJ is the possibility of sequence error, much like the sections of the bridge not lining up properly; even a single base deletion may cause unintended consequences. If the repair occurs in the middle of a gene, the minor error can be enough to disrupt gene function and halt the production of the corresponding protein.
- Homology Directed Repair (HDR) relies on a highly similar (homologous) DNA segment to repair the break—imagine the missing bridge section built elsewhere and helicoptered in to fill the break.
Genome-editing therapy engineers double-stranded breaks to occur at specific locations, activating the intrinsic cell repair pathways: HDR and NHEJ.
Sangamo Therapeutics is applying zinc finger nuclease (ZFN) genome-editing techniques to disrupt the CCR5 gene of HIV patients’ T-cells—this stops the virus from infecting new cells and restores the immune system. The first clinical trials for genome editing are underway for Sangamo’s SB-728, the therapy is currently in Phase II testing .
Zinc finger nuclease genome-editing explained.
To read more, check out Designer Genes: An Introduction to Genome-Editing.
ANTIBODY-DRUG CONJUGATE: IT’S ALL ABOUT THE DELIVERY
Monoclonal antibodies (mAb) are now being used as couriers to deliver a toxic drug to target cells—known as antibody-drug conjugates. In this application, a highly toxic compound is chemically attached to a mAb that recognizes proteins on the surface of a cancer cell. Once bound, the deadly payload is internalized and delivered to the innards of the tumor cells. This therapy is less toxic because it is only delivered to the cancer cells, leaving the neighboring healthy cells in the patient’s body relatively unharmed.
The toxic “drug bomb” attached to the mAb above successfully annihilates the target cell.
While several antibody-drug conjugates are in the midst of development, only two antibody-drug conjugates have made it to market. Roche’s Kadcyla is taking out breast cancer and Seattle Genetics’ Adcetris mutes cancerous lymphocytes in lymphoma.
To read more, check out Biotech’s Battlefront: Monoclonal Antibodies.
BISPECIFIC ANTIBODY: ITS ALL ABOUT THE HYBRID
A bispecific antibody is a genetically engineered protein composed of two different monoclonal antibody fragments, where one fragment binds to the target cell and the other fragment to a killing agent. The killing agent is a specialized T-cell, called a Killer T-cell. This T-cell naturally makes up the front line of the specific immune response. Once activated, Killer T-cells can be highly effective cancer killing machines. However, they often miss tumor cells because tumor cells are not recognized as “foreign”. So the drug discovery challenge has been figuring out how to create an army of T-cells that recognize tumor cells—enter the bispecific antibody.
Blincyto, Amgen’s acute lymphoblastic leukemia treatment, redirects cytotoxic T-cells to target specific tumor cells. Blincyto coasted past the FDA bottleneck ahead of schedule, and gained approval in December 2014 as a first-of-its-kind immunotherapy.
The above image represents the two arms of a bispecific antibody.
To read more, check out The Bispecific Antibody: A Lethal Hybrid.
STEM CELL THERAPY: IT’S ALL ABOUT THE MIX
Stem cell therapy introduces new cells into tissue to treat disease. The scientific challenge is to figure out the exact cocktail of growth factors, hormones, and nutrients required to lead a stem cell down the correct and intended developmental path. Once the cocktail is perfected, scientists can differentiate cell types into their choosing. The ultimate goal is to use these new cells to produce replacement tissue and organs for patients suffering from degenerative diseases or traumatic injuries.
Embryonic stem cells are prized because of their potential to develop into any human tissue—a characteristic called pluripotency. By reactivating the four genes turned off during the progression from embryonic stem cell to specific tissue type, researchers can turn back the hands of time and create induced pluripotent stem cells (IPSC). The IPSC advantage means less chance of rejection by a patient’s body.
To date, the only stem cell-based therapy approved by the FDA is New York Blood Center’s Hemacord, a cord blood product indicated for disorders related to production of blood in the body. Clinical trials are ongoing for stem cell derived therapies for diabetes, stroke, ALS, and spinal cord injury.
To read more, check out Tailoring Stem Cells to Fashion Replacement Organs.
